GUI_ROUNDED_RECT

Vertex format for GUI rounded rectangle shader.

• UV0: Quad-local UV (0..1). Shader maps this into rect-local coordinates for SDF evaluation.

• Color: Fill or outline color.

• Size: Rect width/height encoded in UV1.x/UV1.y.

• Parameters: Corner radius encoded in UV2.x. UV2.y is reserved for future flags.

• StrokeWidth: Outline width in rect-local GUI units. 0 means fill.